Zonadhesin: Characterization, localization, and zona pellucida binding
Zonadhesin: Characterization, localization, and zona pellucida binding
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DOI：
10.1095/biolreprod65.6.1691
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发表时间：
2001-12-01
影响因子：
3.6
通讯作者：
O'Rand, MG
中科院分区：
文献类型：
--
作者：
Lea, IA;Sivashanmugam, P;O'Rand, MG
区域粘附素是一种多结构域跨膜蛋白，被认为是精子与透明带的结合蛋白。本研究对兔睾丸区粘附素进行了测序，分析了其加工、表达、定位和透明带结合。我们发现前体蛋白只存在于睾丸中，蛋白水解过程导致三个片段的形成：p43 （D1结构域），p97 （D2-D4结构域）和p58 （D4结构域c端）。在成熟精子中，p43和p97片段以二硫键二聚体的形式存在。在精子发生过程中，带粘连素mRNA的合成主要发生在原代精母细胞中，而该蛋白在支持细胞和精子细胞中都很丰富。在精子中，该蛋白仅定位于前顶体，但不能用于在活精子上结合抗体。一旦顶体反应被诱导，区域粘附素从精子中丢失，但保留在顶体包裹体中。我们发现重组D4结构域可以结合透明带，并且我们提出在顶体反应启动后，区域粘附素起作用，将顶体覆盖层结合到透明带上。
Zonadhesin is a multiple-domain transmembrane protein that is believed to function as a sperm-zona pellucida binding protein. In this study we sequenced zonadhesin from rabbit testis and analyzed its processing, expression, localization, and zona pellucida binding. We show that the precursor protein occurs exclusively in the testis and that proteolytic processing results in the formation of three fragments: p43 (D1 domain), p97 (D2-D4 domains), and p58 (D4 domain-C-terminal). In mature spermatozoa the p43 and p97 fragments exist as disulfide-bonded dimers. During spermatogenesis, synthesis of zonadhesin mRNA chiefly occurs in primary spermatocytes, whereas the protein is abundant in both Sertoli cells and spermatids. In spermatozoa the protein is localized exclusively to the anterior acrosome but is not available for binding antibody on live spermatozoa. Once the acrosome reaction is induced, zonadhesin is lost from the spermatozoon, but remains with the acrosomal shroud. We show that recombinant D4 domain can bind zona pellucida, and we propose that zonadhesin functions after the acrosome reaction has been initiated to bind the acrosomal shroud to the zona pellucida.